document.write( "Question 11826: hi im having trouble on this problem. \"graph the line perpendicular to the graph of 3x-2y=24 that intersects it at its x-intercepts.\" what i did was get the equation into the yintercept form i think its called like that. y=-12+3/2x. the x-intercept is 3/2 right? and i plot the -12 on the graph right? now i dont know what to do. thank you \n" ); document.write( "
Algebra.Com's Answer #6056 by longjonsilver(2297)![]() ![]() You can put this solution on YOUR website! no, the straight line in \"y-intercept\" form or whatever you want to call it is:\r \n" ); document.write( "\n" ); document.write( "y = (3/2)x - 12... always think of it as y = mx + c ie x term first.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "so, the gradient is 3/2 and the y-intercept is -12. \n" ); document.write( "If you are going to plot this properly, then we need 2 points to join. We now have (0, -12).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The second point we can find easily is the x-intercept, when y=0... \n" ); document.write( "3x-2y=24 \n" ); document.write( "3x = 24 \n" ); document.write( "x = 24/3 \n" ); document.write( "--> x=8 \n" ); document.write( "--> so the point is (8,0)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "This allows you to plot the first equation. How about plotting the second, the equation that is perpendicular?\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "well, it will fit the line y=mx+c again. We need its gradient and y-intercept.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Its gradient is -2/3... 2 lines perpendicular to each other will have their gradients m and n where mn=-1. This is ALWAYS true\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "(eg if one gradient is 3, the other will be -1/3 etc)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "so, we have y = -(2/3)x + c\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "To find c, we need to know a (x,y) pair, which we do, because we know the line goes through the point (8,0), so 0 = -(2/3)(8) + c \n" ); document.write( "-16/3 + c = 0 \n" ); document.write( "c = 16/3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "--> equation is y = -(2/3)x + 16/3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "now to find another point on this line, to draw the straight line... pick the easiest one you can, as ever... so when x=0, y = 16/3, so now you can plot the line.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "jon. \n" ); document.write( " \n" ); document.write( " |